Jackman Reservoir Dam (Franklin Pierce Lake)

Field Descriptions

Dam Name: Jackman Reservoir Dam
Other Name: FRANKLIN PIERCE LAKE DAM
NID ID: NH00199
Longitude: -71.94889
Latitude: 43.11055
County: HILLSBOROUGH
River: NORTH BRANCH CONTOOCOOK RIVER
State: NH
Nearest City: HILLSBOROUGH
Distance: 1 miles
Owner Name: PSNH
Owner Type: Public Utility
Dam Designer: VAUGHAN ENGINEERS, BOSTON
Private Dam? No
Purposes: Hydroelectric
Year Completed: 1926
Dam Length: 1870 feet
Dam Height: 43 feet
Maximum Discharge: 17700 cu ft/sec
Maximum Storage: 12400 acre-feet
Normal Storage: 8360 acre-feet
Surface Area: 486 acres
Drainage Area: 63 square miles
Hazard Potential: High
Emergency Action Plan? Yes
Inspection Date: 2011-11-18
Inspection Frequency: 0
State Regulated Dam? Yes
State Regulating Agency: NH DEPARTMENT OF ENVIRONMENTAL SERVICES DAM BUREAU
Spillway Type: Uncontrolled
Spillway Width: 0 feet
Federal Funding Agency: FRANKLIN PIERCE LAKE DAM
Source Agency:

Dam Safety For Boats

A large amount of water can be released from a dam without any warning at any time and by any means. For example, when the demand for electricity is high, the turbines at a dam may be turned on automatically, resulting in a significant increase in the downstream flow of water in only a matter of seconds.

If there's a need to release water through the sluiceways (outlets at the base of the dam), this operation can also create a great swell of discharged water downstream.

During flood operations, any or all spillway gates across the width of a dam can be opened to release upstream flood water that needs to pass to the next downstream reservoir. Upstream or downstream, even the most experienced boater with the strongest motor is no match for this strong flow of water plunging over a spillway of a dam. Even if you're boating far downstream of a spilling dam, recirculating current can pull a powerful boat upstream toward plunging water that could shred any boat.

Some dams equipped with navigation locks create turbulent water as well. When vessels pass through, strong flow is released near the exhaust ports of the wing wall of the lock.

Warning Systems At Dams

To warn reservoir users of potential danger, warning devices are installed at many dams:




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